Tomado de In Situ Soil Remediation, Archivos case3 y case 4

5.7 Costs

The costs of soil remediation are an important factor when weighing remediation options. In most cases, the least expensive oPtion by which the objective can be attained will be chosen. The Dutch Soil Protection Act allows for deviations from the objective of restoration of the multifunctional properties of the soil, if certain location-specific circumstances apply. These circumstances involve the difference between costs of multifunctional remediation and the costs of an isolation, containment and control (ICC) variant. When calculating remediation costs, the entire remediation period should be considered

It may for instance be advantageous to incur the relatively high costs of cleaning up the contamination source tight away in order to minimize the costs of long term containment. When soil is remediated by means of excavation, the costs of treatment of the excavated soil often constitute a large share of the total remediation costs.

There are two types of costs of in situ soil remediations:

l Non-recurring installation costs: - installation of the in situ system: - installation of pipelines, filters, valves, etc.: - connecting the pumps, etc. - installation of the water and air treatment installations.

2. Operating Costs:

- depreciation of the installation:

- maintenance of the installation (replacement of filter material, periodical

check-ups, costs of activated carbon, discharge of residues, etc);

- Costs of energy;

- environmental supervision and monitoring;

- costs of discharge.

The investment costs of in situ remediation are usually lower than those of conventional remediations, as the installation of air and water extraction and injection means is less expensive than the excavation and treatment of soil.

The (capitalized) annual operating costs of in situ remediations are often quite high. As the remediation may take several years, the costs of depreciation, energy and monitoring are high, compared to conventional techniques. Given the wide variety of circumstances related to infrastructure, buildings, depth of the contamination. etc., it is not possible to quote standard prices.

Figure 5.l2 is a graphical representation of the operational costs of the in situ remediation of mineral oil contaminations. These COSts were derived from real practice cases, and have been compared with the costs of conventional excavation and off-site treatment costs.

The practice cases were averaged by means of a regression analysis.

Particularly where smaller soil volumes are concerned. in situ remediation is often more expensive than excavation. This is due to the relatively high operating costs of in situ remediation. In these cases, in situ remediation is only chosen when it is technically impossible to remove the contaminants by means of excavation.

If larger quantities of soil are concerned (from 2,000 to 3,000 m3) in situ remediation becomes relatively less expensive, and such a remediation will be chosen wherever technically feasible.

Figure 5.12 Costs of In situ remediation of petroleum hydrocarbons

Another contaminant for which in situ remediation costs are high is chlorinated solvents. The treatment of extracted groundwater - and to a lesser degree, of soil vapour - largely determine the costs of the in situ remediation of these contaminants .